Squealing can be from belt slippage, but I would expect that in 1st gear.
I've heard of people with alternators going out that initially were misdiagnosed as transmission noise.
Definately not rear end clutch packs.
5r55s auto trans
in Explorers and some early year s197's had problems with low reverse planetaries and made a whining sound.
That noise mostly shows up as a whine in the shift from 1st to 2nd, and maybe a much lesser whine from 2nd to 3rd.
Another source can be the transimission valve body separator plate/gasket.
To a degree, the auto trans
do make a low/reverse whine, but most of the time you really have to listen for it. If you have an aftermarket exhaust, and/or your windows are down, you pretty much don't notice. That noise is normal though.
I have a V6 with the same 5r55s trans
and it did make a lot more noise than normal. Went round and round with the dealer. The usual stuff you would expect. They finally tore it apart and the head tech said the low reverse planetaries showed abnormal wear, so they replaced a bunch of parts under warranty.
I got the car back, and the noise was different but still there, and still loud.
They brought out a Ford field engineer and we both test drove the car. Afterwards, he wrote up a report and got me a replacement transmission which was much quieter.
The noise didn't bother me, but I was paranoid about stuff breaking down. I was holding off on a bunch of mods because I didn't want the dealer to blame the mods for anything that might break in the transmission.
2007 Satin Silver V6 / Explorer Express X-Charger #67 - Xtreme 2.6 - INTERCOOLED!
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